Process and device for crimping and heat-setting of yarns made from synthetic linear high polymers

ABSTRACT

PROCESS AND DEVICE FOR CRIMPING AND HEAT-SETTING OF YARNS MADE FROM SYNTHETIC LINEAR HEATER HIGH POLYMERS, ESPECIALLY POLYAMIDES AND POLYESTERS, WHICH COMPRISES EXTENDING THE PATH OF THE YARN BETWEEN THE STRETCHING ZONE AND THE ENTRANCE TO THE CRIMPING ZONE WHILE REDUCING THE HEAT DEVELOPED IN THE STRETCHING OPERATION, THEREAFTER SUBJECTING THE YARN TO COMPRESSION CRIMPING AND HEAT-SETTING THE CRIMPED YARN RELEASED FROM THE CRIMPING ZONE IN A TWO-STAGE OPERATION IN SUBSEQUENT STEPS AT CONTROLLED TEMPERATURES.

Jan. 12, 1971 G. BUSCHMANN ETAL 3,553,803

PROCESS AND DEVICE FOR CRIMPING AND HEAT SETTING OF YARNS I MADE FROMSYNTHETIC LINEAR HIGH POLYMERS Filed Jan. 5, 1969 1 INVEN'TOR GERHARDBUSCHMANN ERICH MEWES ATTORNEYS United States Patent 3,553,803 PROCESSAND DEVICE FOR CRIMPING AND HEAT-SETTING OF YARNS MADE FROM SYN- THETICLINEAR HIGH POLYMERS Gerhard Buschmann and Erich Mewes, Wilhelm PieckStadt Guben, Germany, assignors t0 VEB ChemicfaserkombinatWilhelm-Pieck-Stadt Guben, Wilhelm Pieck Stadt Guben, Germany Filed Jan.3, 1969, Ser. No. 788,845 Int. Cl. D02g 1/12 US. Cl. 281.6 6 ClaimsABSTRACT OF THE DISCLOSURE Process and device for crimping andheat-setting of yarns made from synthetic linear heater high polymers,especially polyamides and polyesters, which comprises extending the pathof the yarn between the stretching zone and the entrance to the crimpingzone while reducing the heat developed in the stretching operation,thereafter subjecting the yarn to compression crimping and heat-settingthe crimped yarn released from the crimping zone in a two-stageoperation in subsequent steps at controlled temperatures.

Crimping processes for yarns made from synthetic fibers are alreadyknown having the object of imparting to the smooth yarn a wool-liketexture, an increased fullness, and a higher resilience. The expressionyarn used herein is intended to include monoas well as multifilamentproducts. The above mentioned object is accomplished by causing the yarnto pass into a crimping chambet at relatively high speed and by pressingthe yarn onto a plug already present in the chamber. The bending in thisprocedure occurs in a preferred direction, but this does not exclude thebending from occurring in any other direction. The introduction of theyarn into the crimping chamber may be effected by pneumatic, hydraulic,or mechanical devices.

At any rate, the yarn entering the chamber has to be heated beforeintroduction. The heating may be brought about by heating rails, orother heating elements, operated by steam, hot gases, liquids,electrical resistance or induction, or in any other desired manner.

Some crimping devices are further known which are of the compressionchamber type, in which immediately before the crimping a stretching ofthe yarns occurs and wherein the resulting partial successive softeningof the yarn is made use of in the crimping process, so that apre-heating of the yarn may be dispensed with.

The yarn entering the crimping chamber may already have a preliminarytwist, because this will yield a closed bundle of thread which passesthrough the chamber more smoothly than an untwisted fiber. Thepreliminary twist may already be present on the yarn discharge device,or it may be brought about by means of rotating devices while the yarnis drawn off said device. The latter device and method of operation maybe more desirable, since it permits satisfactory handling of the yarndischarge device as well as favorable conditions for the yarn forentering the crimping chamber.

For improving the degree of heating-setting of the crimped yarn, thereare devices known in which threads are after-treated in stabilizingchambers arranged in series with the crimping chamber; there, treatmentis effected with hot or cold agents. When heat-setting is done in thecrimping chamber, either direct or indirect heating means may be used.In both cases steam, liquid or gaseous heating media or electric energycan be used. The same direct or indirect heating means can be employedwhen the heatsetting is effected in the stabilizing chambers. It is alsoPatented Jan. 12, 1971 known to cause the textured yarn to pass heatingand cooling zones arranged directly in series.

Another known means for setting the unset, textured yarn leaving thestabilizing chamber is the use of heating bars or rails or similardevices; this method is used for obtaining a lasting crimp and forobtaining threads of uniform physical characteristics to improve dyeingproperties and decrease the tendency of shrinking.

However, the known processes and devices have the drawback that they donot lend themselves for the production of yarns having a predeterminedcrimping degree, which is necessary for the subsequent processing indifferent sectors of the industry. For application in various fields, agraded degree of crimping is required. Thus, for instance, the rugmanufacturers ask for a low crimp, the manufacturers of materials forfurniture coverings request a higher crimp and the manufacturers ofknitted fabrics for wearing apparel ask for the highest degree.

Moreover, the degree of heating-setting accomplished up to now is notsatisfactory in some cases, so that upon further processing considerabledifiiculties are encountered, such as excessive shrinkage, or extensionof the crimped yarn during dyeing and winding on reels.

It is an object of the present invention to provide a process and devicewhich will eliminate the short-comings of the known methods and devices.

More particularly, it is an object of the invention to provide meanswhereby the degree of crimp of the fibers processed is variable within acertain range and will favorably affect the further processing indifferent fields of application.

Other objects and advantages of the present invention will becomeapparent from the following detailed description in combination with theaccompanying drawing.

For a better understanding it should here be noted that by the degree ofsetting of the crimped yarn we mean to indicate a means of measuring thedegree of orientation of the molecules in the direction of the threadand for the inner structure of the thread. On the other hand, the degreeof crimping defines a ratio of lengths of sections of the thread undertension and without tension, when loads are applied which depend on thethickness of the thread in each case. The degree of crimping isinfluenced positively by the choice of the temperature to which the yarnis preheated before entering the crimping chamber.

In accordance with the invention it was found that a graded adjustmentof the degree of crimping can be travelled by the yarn between thestretching and the crimping, while decreasing the heat of stretching byinserting an appropriate device for adjustably lengthening the path;such a device may eg be :a guide roll for changing the direction of thetravelling yarn. The change of the path may be in stages or occurwithout interruption. The latter may be brought about by slidablyarranging the guide roller for instance in a slot.

For the improvement of the setting, the arrangement according to theinvention provides that the crimped yarn leaving the crimping chamber istreated in a receiving chamber directly following the crimping chamber,while relieved from stress; the treatment is performed with a suitableheating agent, preferably steam, which will cause shrinkage andheat-setting. The heating agent is fed into the device about at thetransition zone between crimping chamber and receiving chamber. In orderto increase uniformity and stabilization of the desired setting, thetreat ment in the receiving chamber will be followed by aftersetting ina heating device, preferably heating rails, bars or heated godets. Byselecting the desired temperature of this heating device and by changingappropriately the time while the crimped threads are made to stay on theheated surfaces, an accurate adjustment of the degree of setting can beachieved.

The invention has extended the field of application ofcompression-crimped yarn to an unexpected degree. For instance, in themanufacture of knitted goods there is a far wider applicability. Thesuggested lengthening of the path of the yarn, particularly thecombination of the last stretching godet with a guide roller on whichthe yarn is repeatedly wound, has the added advantage that variations ofthe speed of travel within the stretching field are avoided which inturn eliminate fluctuation in the thickness of the crimped yarn.

The better setting of the crimp is also an important improvement of theproduct and an advantage for the industries concerned.

The invention will now be explained in an example with reference to theaccompanying drawing, the sole figure of which schematically illustratesa device for carrying out the process according to the invention.

In the drawing, a spool 1 is shown on which a yarn 13 is collected andfrom which it is withdrawn by a pair of rollers 6; arranged in its pathare a guide roller 14 and two stretching godets 2 and 3, the latterbeing rotated at a higher speed than the former. The yarn is nextpassing a deflecting roller 4 and from there reaches a funnel 5 at theentrance of the crimping chamber 7 of known design. The deflectingroller 4 is mounted on a plate 19. The shaft (not shown) of the roller 4is supported in a slot 18 in the plate 19. The roller 4 may be set atany point along the slot 18 and, when desired, adjusted to a newposition along the slot 18. Crimping occurs by compression of the yarnagainst a flap which defines the downstream end of the crimping chamber7. The flap 15 is rigidly connected to a lever 16 and this assembly ispivotally mounted to the wall of the crimping chamber 7 at the junctureof the flap 15 and the lever 16. A weight 17 suspended from the free endof the lever 16 maintains the compression in the crimping chamber.

As shown in the drawing, the yarn 13 can be wound around the deflectingroller 4 and the godet 3 several times in a predetermined manner wherebythe length of the path traversed and the cooling of the yarn arecontrolled and thereby the crimp accomplished is likewise determined.Typically, distance between godet 3 and roller 4 is about cm.

The crimping chamber 7 is followed by a receiving chamber 8 of largercross section so that the stack of yarn leaving the crimping chamberunder pressure can then expand.

In the state of pressure relief, the crimped stack is treated with asuitable heating agent, for instance steam, admitted through a conduit9; the yarn is thereby subjected to shrinkage and becomes set. Thecrimped, shrunk and set yarn is then withdrawn from the stack over atensioning device 10 and passed over another heating device 11 beforebeing wound onto a spool 12; by the passage through the heater 11, andafter-setting of the yarn takes place. The temperature in the heater 11should exceed that in the receiving chamber 8. When polyamides are thustreated, the yarn temperature in the chamber 8 should preferably be fromto 140 C. and the yarn temperature at heater 11 should preferably befrom to 180 C. and should not exceed 190 C.

What is claimed is:

1. A process for crimping and heat-setting yarns made from syntheticlinear high polymers, which comprises variably lengthening the path ofthe yarn between a stretching zone and the entrance to a crimping zonefor reducing the heat developed in the stretching operation, thereaftersubjecting the yarn to compression-crimping in the crimping zone, andheat-setting the crimped yarn released from the crimping zone in atwo-stage operation at controlled temperatures.

2. The process according to claim 1, wherein the temperature in thefirst heat-setting step is lower than the temperature in the secondheat-setting step.

3. The process according to claim 2 which comprises subjecting polyamideyarn to the crimping and heat-setting operations and maintaining thetemperature in the first stage at 105 C. to C. and in the second stageat 120 C. to C.

4. A device for crimping and heat-setting yarn made from high-molecularweight linear synthetic polymers which comprises a crimping chamber, areceiving chamber arranged in series therewith, means for feeding saidyarn from a source into saitfcrimping chamber, at least one stretchingroller in the path of said yarn between said source and the withdrawalmeans, a direction changing deflecting guide roller between thestretching roller and the Withdrawal means, said stretching roller andsaid guide roller serving for variation of the path length traversed bysaid yarn so as to dissipate some of the heat developed therein duringthe stretching operation, first heating means near the outlet of thecrimping chamber, second heating means arranged in the path of the yarntraversed after the receiving chamber, and final spooling means for saidyarn, said heating means acting as heatsetting means for the crimpedyarn.

5. The device according to claim 4, wherein the stretching meansconsists of a plurality of godets, the last godet together with saiddeflecting guide roller capable of receiving the yarn in a number ofturns for varying the length of the yarn path traversed before the yarnarrives at the crimping chamber and thereby the degree of crimp effectedin the yarn.

6. The device according to claim 4 wherein said first heating meansconsists of steam and said second heating means consists of an electricheating device.

References Cited UNITED STATES PATENTS 3,425,106 2/1969 Mattingly 28-1.63,441,989 5/1969 Clarkson et al 281.6

LOUIS K. RIMRODT, Primary Examiner U.S. Cl. X.R. 2.872.14

